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15 November 2008

Power-Saving Tips From Biochemistry

Need to lower the electric bill? You could learn a thing or two about conservation from your body's own cells.

Each one possesses a highly evolved system of energy efficiency that consists of regulatory enzymes (1). These catalysts can be activated and deactivated depending on conditions in the cell (1p649-651).

When strategically located as a first step or near-first step of a metabolic pathway, a regulatory enzyme acts as biochemical light switch.(2) The enzyme switches "on" and "off" effectively speeding up or slowing down pathway production and preventing any drain of effort.(2)

An example of three regulatory enzymes in action can be found in glycolysis, the 10-reaction pathway used to produce energy from carbohydrates(1p726):

1. Hexokinase catalyzes the first reaction of the pathway and is inhibited by high concentration of its own product.

2. Phosphofructokinase, the key regulatory enzyme, catalyzes the third reaction and is allosterically inhibited by glycolysis product, ATP, and intermediate, citric acid. This is an example of feedback inhibition.

3. Pyruvate kinase catalyzes the last reaction. Because it is activated by activation of phosphofructokinase through feedforward activation, it is allosterically inhibited by inhibition of phosphofructokinase.

In other words, the last enzyme in the pathway is saying, "First and third one out, don't forget to turn off the lights."

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I'm a science and health writer based in the Gilbert, Ariz., with a passion for good food combined with a good story. My background is in science communications with a master's of science degree in human nutrition and a bachelor's of arts degree in English. I've written for a variety of publications including Scientific American, Outside Online, the American Society for Nutrition's Nutrition Notes Daily, and the Institute of Food Technologists' Food Technology print magazine. I'm an active member of several respected organizations including the National Association of Science Writers and the American Association for the Advancement of Science. I'm also interested in wildlife conservation and am a member of the National Audubon Society and the American Society of Naturalists.